Generalised Anxiety Disorder Assessment (GAD-7)
The Generalised Anxiety Disorder Assessment (GAD-7) is a brief measure for symptoms of anxiety, based on the generalised anxiety disorder diagnostic criteria described in the Diagnostic and Statistical Manual of Mental Disorders (DSM). The GAD-7 assessment asks patients to evaluate their level of symptoms over the last two weeks. When administered on multiple occasion at the start, middle and end of treatment, responses can be used to track treatment progress over time.
Given the simple language used in the assessment it is appropriate for individuals as young as 14 years. When used as a screening tool, further evaluation is recommended when the score is 10 or greater.
Using a cut-off score of 10 the GAD-7 can be used as a screening tool for three other common anxiety disorders – panic disorder (sensitivity 74%, specificity 81%), social anxiety disorder (sensitivity 72%, specificity 80%), and post-traumatic stress disorder (sensitivity 66%, specificity 81%) (Kroenke, et al. 2007).
Validity and Reliability
Lowe et al. (2008) investigated the validity and reliability of the GAD-7. Confirmatory factor analyses substantiated the 1-dimensional structure of the GAD-7. Internal consistency was identical across all subgroups (alpha = 0.89). Intercorrelations with the PHQ-2 and the Rosenberg Self-Esteem Scale were r = 0.64 (P < 0.001) and r = -0.43 (P < 0.001), respectively. As expected, women had significantly higher mean (SD) GAD-7 anxiety scores compared with men [3.2 (3.5) vs. 2.7 (3.2); P < 0.001]. In a normative sample approximately 5% of subjects had GAD-7 scores of 10 or greater, and 1% had GAD-7 scores of 15 or greater.
Norms were developed by Lowe et al. (2008) with a German sample of 5030 subjects (53.6% female) with a mean age (SD) of 48.4 (18.0) years.
Using the threshold score of 10, the GAD-7 has a sensitivity of 89% and a specificity of 82% for generalised anxiety disorder.
Scoring and Interpretation
A raw score (from 0 to 21) is presented as well as a percentile rank based on the Lowe et al. (2008) community sample. Given that females score slightly higher than males, a percentile for each gender is presented – the appropriate gender percentile should be selected for interpretation.
Percentiles provide a useful context for comparing a respondents results with a normative sample. A percentile of 50 represents typical (and healthy) patterns of responding, while higher percentiles represent higher levels of anxiety symptoms.
Spitzer, R. L., Kroenke, K., Williams, J. B., & Löwe, B. (2006). A brief measure for assessing generalized anxiety disorder: the GAD-7. Archives of internal medicine, 166(10), 1092-1097.
Kroenke K, Spitzer RL, Williams JB, et al; Anxiety disorders in primary care: prevalence, impairment, comorbidity, and detection. Ann Intern Med. 2007:146(5):317-25.
Löwe, B., Decker, O., Müller, S., Brähler, E., Schellberg, D., Herzog, W., & Herzberg, P. Y. (2008). Validation and standardization of the Generalized Anxiety Disorder Screener (GAD-7) in the general population. Medical care, 46(3), 266.